The struggle between the Papacy and the Empire, ending, as it did, in the downfall of the House of Hohenstaufen, put an end to the old conception of the universal monarchy presided over by the Emperor and the Pope. A new tendency began to make itself felt in European politics. Hitherto the feudal system, on which society was based, had served as a barrier against the development of royal power or the formation of united states. Under this system the king was sometimes less powerful than some of his nominal subjects, and was entirely dependent upon the good-will of the barons for the success of any action he might take outside his own hereditary dominions. This was the real weakness of the system, and so long as it remained the growth of Nationalism was impossible. Gradually, however, by the exertions of powerful sovereigns the power of the barons was broken, the smaller states were swallowed up in the larger ones, and the way was prepared for the rise of the nations of Modern Europe. In France the policy of centralisation begun in the thirteenth century, was carried to a successful conclusion in the days of Louis XI. (1461-83). The English provinces, Aquitane, Burgundy, and Brittany, were all united to form one state, knowing only one supreme ruler. In Spain the old divisions disappeared almost completely with the union of Castile and Aragon under Ferdinand (1479-1516) and Isabella the Catholic (1474-1504), and with the complete destruction of the Moorish power by the conquest of Granada (1492). In England the slaughter of the nobility in the Wars of the Roses left the way ready for the establishment of the Tudor dominion. As part of the same movement towards unification Henry VIII. was declared to be King of Ireland instead of Feudal Lord, and serious attempts were made to include Scotland within his dominions. Inside the Empire similar tendencies were at work, but with exactly opposite results. The interregnum in the Empire and a succession of weak rulers left the territorial princes free to imitate the rulers of Europe by strengthening their own power at the expense of the lower nobility, the cities, and the peasantry; but, having secured themselves, they used their increased strength to arrest the progress of centralisation and to prevent the development of a strong imperial power.